Apparatus for supplying metal to an evaporation source in a metallizing operation



United States Patent Inventors Appl. No.

Filed Patented Assignee Raymond D. Bowdey; Theodore VanVorous, Boulder, Colorado 779,887

Nov. 29, 1968 Dec. 8, 1970 The Dow Chemical Company Midland, Michigan a corporation of Delaware APPARATUS FOR SUPPLYING METAL TO AN EVAPORATION SOURCE IN A METALLIZING Primary Examiner-Stanley H. Tollberg Attorneys-Griswold and Burdick, V. Dean Clausen and William R. Norris ABSTRACT: Apparatus for feeding metal strands into an evaporation source in a vacuum system for vapor deposition on a substrate, such as metal. Short sections of wire are positioned in grooves located on the periphery of a rotatable drum. An indexing motor rotates the drum one groove at a time to position a wire strand in contact with a feed roller mechanism. The feed roller mechanism which is operated by a sprocket and bead chain drive, advances the wire through a guide means and into the evaporation source. With this apparatus a number of short wire sections may be sequentially fed into an evaporation source in a semiautomatic operation.

PATENTEU BEE 8 197B SHEET 2 OF 2 IN VENTORS. O D. Bowo'ey dare Van l/orou;

QQ a Raymon Theo 002 Kym H WW APPARATUS FOR SUPPLYING METAL TO AN EVAPORATION SOURCE-IN A METALLIZING OPERATION BACKGROUND OF THE INVENTION number of wire strands, one strand ata time, into an evapora- 7 tion source in a vacuum deposition process.

The invention described-herein was made in the course of, or under, a contract with THE UNITED STATES ATOMIC ENERGY COMMISSION.

In certain metallizing operations, which might be generally described as vacuum deposition, metal vaporplating, vacuum welding and the like, the operation is generally conducted in a vacuum environment, since it is desired to avoid oxidation, slag formation, andother undesirable effects in the coating deposit or weld joint. Such operations are generally conducted in various vacuum systems such as dry boxes, vacuum chambers, bell jars, and the like. One'method presently used in such operations to provide the metal vapor deposit involvesfeeding a metal strand or wire from a spool through a hand-operated gun and into an evaporation source, such as a set of electrodes, to evaporate the metal and thus deposit the vaporized metal on the intended substrate.

The hand gun technique has certain disadvantages. For ex ample, because of the size of the 'feed'spool-gunassembly it is difiicult to conveniently operate in the confines of the vacuum chamber, since the gun interferes with positioning of parts racks, jigs and other devices in the vacuum chamber. Additionally, in certain metal evaporation operations brittle metals, such as tungsten, beryllium, uranium, chromium and nickel wire are employed as the vapor depositing material. Because of their brittle'characteristicssuch wire materialsare generally not availableinspool form and the wire must be cut into short sections for use in the feed gun. The design of the feedgun, however, makes it incapable of completely feeding through an entire wire section, so that a small piece of wirealways remains in the gun after each section is run through.

This, of course, results in a substantial amount of scrap over a period of time. A further disadvantage of the hand gun feed is thus disrupt the desired feed rate into the melt zone. Such a disruption in the feed rate] usually results in a'discontinuity in the film being deposited on the metal substrate. A still further disadvantage of the hand gun feed is that when .the'wire section is exhausted, the vacuum system must be cooled down and vented in the shutdown operation before a new .piece of wire can be added to the gun. After installation of the new wire the system must again be pumped down to the desired pressure before the coating operation can resume. The length of time and inconvenience involved in these various manipulations can be a costly factor in the overall time required for completing a metal evaporation operation.

OBJECTS OF THE INVENTION A broad object of this invention is toprovide a simple and compact apparatus useful in a semiautomatic operation to feed a metal strand into an evaporation source in a metallizing operation. p

A more specific object of the invention is to provide a semiautomatic device which may be used in a vacuum system to sequentially feed metal wire sections into an evaporation source in a metal vapor deposition technique.

Another object of the invention is to provide a device as described above which is particularly adapted for feeding brittle metal wire sections into an evaporation source for vapor deposition on a substrate.

SUMMARY OF THE INVENTION These benefits and other advantages in accordance with the invention are achieved by providing an apparatus for feeding metal wire sections into an evaporation source for vapor deposition of the metal on a substrate. The present apparatus generally includes a base member having mounted thereon a hollow cylindrical housing and a cylindrical drum member, the drum member being rotatably mounted in said housing and adapted for driving engagement with anindexing motor. The drummember-contains a plurality of grooves on the periphery thereof which serve as means for retaining short sections of wire. An indexing motor rotates the drum, one groove at a time, to accomplish sequential feeding of each wire section into an evaporation source. Appropriate feed rollers, a guide roller and wire guide means mounted on the base member and adapted to cooperate with each wire section rotated into position on the drum member, control the feed rate of the wire sections into the evaporation source. The feed rollers aremounted on'shafts rotated by drive sprockets, the sprockets in turn being driven by an electric motor through a bead chain linkage connecting the respective sprockets.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side elevation view, partly in section, of an apparatus or device embodying the features of this invention.

FIG. .2 is a cross-sectional view taken as indicated on line 2 2 of FIG. 1.

FIG. 3is another cross-sectional view taken as indicated on line 3-3 of FIG. 1.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring more particularly to FIGS. 1-3 of the drawing, there is illustrated a wire feeding device or apparatus 10 according to-one embodiment of this invention. The apparatus l0includes a hollow, generally cylindrical housing, designated as a wire drum housing 12, the rear'portion thereof having an integral outwardly directed flange 12a and the forward portion thereof having an integral inwardly directed flange 12b. A generally cylindrical drum, designated as wire drum 14, is rotatably mounted within the drum housing 12 by means of a front journal 14a which rides in a bearing 16 seated in flange 12b of housing 12 and a rear journal 1412 having a central bore portion 140 therein which engages the shaft of a conventional indexing motor (not shown). A series of generally flat-bottomed grooves 14d, which extend lengthwise of and are located around the periphery of wire drum 14, provide a magazine means for holding short sections of metal strands or wires to be delivered to'an evaporation source by the apparatus 10, as will be explained in more detail hereinafter. In the preferred embodiment of apparatus '10 as illustrated herein, the grooves 14d in wire drum 14 are of a size which will accommodate a wire section about Az-inch diameter by 6inch length and the drum is fabricated with 12 grooves therein. It will be understood, however, that it is within the scope of this invention to provide a wire drum having any number of wire receiving grooves therein, within practical limits, the grooves being made to a size which would accommodate wire sections of various diameters and lengths. Numeral 18 refers to a U-shaped base member on which the wire 'drum housing 12 is mounted or secured by means of cap screws 20, 21 which connect flange 12a with the rear portion of base member 18. A top for the apparatus 10 is provided by a support plate 22 comprising a generally rectangular, flat plate secured at one end to flange 12a with cap screws '24 and at the opposite end to a forward wall of base member 18 with capscrews 26.

Referring particularly to FIG. 1, a short section of wire 28 is shown as it would appear lying in a groove 14d of wire drum 14, the groove having been rotated to bottom center position of drum 14, from which position the wire section 28 can be advanced by a feed roller 38 through a secondary wire guide means 34, beyond which it is engaged by a feed roller 30 and a guide roller 32, which further advances it through a main wire guide means 36 and thence into an evaporation source, as will be explained in more detail hereinafter. A portion of a wire section, as designated by the numeral 28a, better illustrates the feeding of the wire section through guide means 34, feed roller 30, guide roller 32 and guide means 36.

Means for initiating the advance of the wire section 28 into the secondary wire guide means 34 is provided by a feed roller 38, as defined by a wheel or roller having notches or serrations on the periphery thereof. The feed roller 38 is mounted on a shaft 40 which is journaled in bearings 42, 44 and the bearings in turn are seated in a centering yoke 46. Centering yoke 46 is pivotally mounted between the spaced apart wall members 18a, 18b of base member 18 by a pin or shaft 48 which extends between these walls. Centering yoke 46 provides means for applying tension against feed roller 38 to urge the roller upwardly or downwardly as desired to regulate the forward advance of wire section 28 through the apparatus 10. The tension on yoke 46 is regulated by a machine screw 50, which threadedly engages a support bar 52 and is biased against a shoulder portion 46a of yoke 46 by a coil spring 54. The support bar 52 rests in notched out portions in the wall members 18a and 18b and is secured to the wall members by cap screws 56 and 58.

Because of the upward tension applied against feed roller 38 to aid the forward advance of the wire section 28 the feed roller has a tendency to ride upwardly against wire drum 14 once the rear end of the wire section clears the feed roller. This, of course, can cause binding of the drum l4 and interfere with proper indexing to the next position. This problem is alleviated in the embodiment illustrated herein by a machine screw 47, the head portion of which threadedly engages shoulder 46a of yoke 46 and the end of which abuts against the lower surface of support bar 52. The screw 47 thus acts as a stop member which limits the upward travel of roller 38 to a point where it will not ride against drum 14.

Means for driving the feed roller 38 is provided by a first drive sprocket 60, which is mounted on shaft 40 exterior to the rear section of wall member 18b of base member 18. The driving force for sprocket 60 is provided be a bead chain 62 which links sprocket 60 with a second drive sprocket 64, which in turn is driven by an electric motor (not shown) as explained more fully hereinafter.

The secondary wire guide means 34 comprises a weldment including a nozzle portion 34a with a central bore therein and an integral leg portion 34b, as defined by a right-angle bend rod. Nozzle portion 340 is horizontally alined with an opening 66 in flange portion 12b of wire drum housing 12. The alinement is maintained by extension of leg portion 34b of the guide means through an opening in the forward wall of base member 18. A set screw 68 holds the leg portion 34b in the desired position in the wall of base member 18. In the practice of this invention, the secondary wire guide means 34 may be omitted when wire sections exceeding about 0.125 inch in diameter are employed in the metallizing operation. However, when using either ductile or brittle wire sections having diameters smaller than 0.125 inch, it is preferred to use the wire guide means 34 in the apparatus 10, since the smaller wire generally does not have sulficient body or rigidity to properly feed through the feed roller 30 and guide roller 32 and into guide means 36.

The main wire guide means 36 comprises a unitary nozzle member consisting of a first nozzle portion 36a and a second nozzle portion 36b, the second nozzle portion including a flared base 36c. Guide means 36 is threaded into the forward wall 18c of base member 18 with the flared base 36c fitting flush against the outside surface of wall 18c. A central bore extending completely through the unitary nozzle member is horizontally alined with the central bore portion of nozzle portion 34a of guide means 34. i

Means for advancing a wire section 28a through guide means 34 and guide means 36 and thence into an evaporation source is provided by the feed roller 30 in conjunction with the guide roller 32. Feed roller 30 (like feed roller 38) is in the form of a wheel or roller having peripheral notches or serrations therein. Guide roller 32 is a wheel having a peripheral V- groove therein. Feed roller 30 is mounted on a shaft 70 which is journaled in bearings 72, 74 and the bearings in turn are seated in the wall members 18a, 18b, of base member 18. The guide roller 32 is mounted on a shaft 76 which is journaled in bearings 78, 80 and the bearings in turn are seated in a centering yoke 82. Centering yoke 82 is identical in construction and function to the centering yoke 46. Centering yoke 82 is pivotally mounted between the spaced apart wall members 18a, 18b of base member 18 by a pin or shaft 84 which extends between these walls. Yoke 82 provides a means for applying tension against the guide roller 32 to urge the roller upwardly or downwardly as desired to regulate the forward advance of a wire section (such as represented by wire section 28a) through the apparatus 10. The tension on yoke 82 is regulated by a machine screw 86, which threadedly engages a support bar 88 and is biased against a shoulder portion 82a of yoke 82 by a coil spring 90.

Support bar 88 extends across the vertically disposed surfaces of wall members l8a 18b of base member 18 and is secured to the wall members with cap screws 92, 94. Means for driving the feed roller 30 is provided by the second sprocket 64 which is mounted on shaft 70 exterior to the forward'sections of wall member 18b of base member 18. Power to drive the sprocket 64 is supplied by a conventional electric motor (not shown). The motor is positioned externally of the vacuum chamber (or whatever system is used for the metallizing operation) in which the apparatus 10 is placed and drives the sprocket 64 through a vacuum rotary seal unit and a flexible drive shaft which engages the shaft 70. As mentioned earlier, the driving power for the first sprocket 60 is provided by thesecond sprocket 64 (the driven sprocket) as transmitted through the bead chain 62 which engages both sprockets.

For certain metallizing operations it is necessary to feed the wire section 28 into the evaporation source at a downward angle. Where this is done the wire section 28 may slip out of the guide means 36 once the rear end of the wire section clears feed roller 30 and guide roller 32 and is, therefore, no longer held or gripped by these rollers. When a wire section of a duetile metal is used, the wire may be effectively fed into the evaporation source without slippage guiding it through a gripper tube (not shown), as defined by a piece of tubing having external threads on one end which engage internal threads 37 in the bore of nozzle 36. A slight bow or bend near the open end of the tubing (the end next to the evaporation source) kinks the ductile metal and thus provides a gripping action which keeps the wire section from slipping out of the tube. The gripper tube may be fabricated of molybdenum or similar materials capable of withstanding the high temperatures in the immediate area of the evaporation source. For brittle wire sections a similar piece of tubing (not shown) is inserted in nozzle 36, but the tubing is a straight piece with no bend at the open end. Gripping action for the brittle wire is provided by a thimble (not shown) which fits over the open end of the tube and is split down the sides at various points to provide leaf-spring finger portions. The wire passing through the finger portions forces them outwardly and thus provides the necessary gripping action on the wire section. Suitable materials for the gripper thimble include beryllium copper, or other materials capable of withstanding the high temperatures of the evaporation source.

OPERATION In a typical operation of the present invention the wire drum 14 is fully loaded by placing a short section of wire 28 in each of the 12 grooves 14d. The wire can be either a brittle metal, such as uranium or beryllium, or a ductile metal such as aluminum or gold. Inone embodiment of the invention, as illustrated herein, the wire sections measure about iii-inch diameter by 6-inch length. The loaded drum 14 is inserted in the drum housing 12 so that it is rotatably mounted therein as described hereinbefore. A conventional rotary solenoid indexing motor (Digimotor, Ledex, inc. 12 positions (not shown) is mounted adjacent the flange portion 12a of housing 12' such that the motor shaft engages bore portion 140 in the rear journal 14b of drum 14. The apparatus is then placed in a vacuum chamber, such as the type generally used for a metal evaporation process. The apparatus is positioned in the chamber in a manner such that the wire section will feed into an evaporation source, such as a resistance or electron bombardment heated surface, at an angle. The angle of positioning should be such that the apparatus 10 is not interposed between the evaporation surface and the metal object to be coated. More specifically, the apparatus 10 may be positioned at any angle to the evaporation source which does notproduce a shadow on the surface to be coated and at the same time results in maximum impingement of the metal vapor on this surface.

The indexing motor is turned on to initiate rotation of the wire drum l4 and the motor associated'with shaft 70 is 33180 turned on to actuate driving of the sprocket'64. As each groove 14d rotates to bottom center position of the drum 14 the wire section 28 is engaged by the feed roller 38 and steadily advances through opening 66 in housing 12 and thence into nozzle portion 34a of guide means 34. As the forward end of the wire section (as represented by'section 28a) leaves the nozzle 34a it is engaged by feedroller 30 and guide roller 32 and steadily advances through the bore portion of guide means 36 and toward the evaporation source.

An appropriate counter or indicator device (not shown) associated with the external drive system (as represented by sprockets 60, 64 and the driving motor) enables the operator to ascertain when a given wire section has completely passed through its respective groove 14d at the bottom center position in drum 14.-At this point the operator can energize the indexing motor to rotate the drum 14 and bring the'next groove into bottom center position to start another wire section through the apparatus. Alternatively, drum 14 can be indexed automatically by connecting an automaticpulsing switch to the counter device.

We claim:

1. An apparatus for feeding metal wire sections into an evaporation source which includes, in combination:

I. a base member which:

A. has a forward wall member;

B. has spaced apart upstanding side wall members;

II. a hollow, generally cylindrical housing which:

A. has a rear flange member integral with a rear portion of the housing which:

1. is secured to the base member; 2. has an indexing motor mounted thereon;

B. has a forward flange member integral with a forward portion of the housing, said flange having an opening therein;

III. a generally cylindrical drum member'which:

A. is rotatably mounted, in the flange members of the cylindrical housing;

B. has means thereon adapted for engagement with the indexing motor;

C. has wire retaining means positioned on the periphery of the drum;

IV. a first roller means for engaging the metal wire section, the roller means being rotatably mounted on the base member;

V. means for regulating the tension on the first roller means which:

A. is mounted on the base member;

B. engages the first roller means;

V]. a guide roller means for engaging the metal wire section which;

A. is mounted on the base member;

B. is positioned ahead of the first roller-means;

VII. means for regulating the tension on the guide roller means which:

A. is mounted on the base member;

B. engages the guide roller;

C. is positioned ahead of the first roller means;

VIII. a second roller means for engaging the metal wire section, the roller means being mounted on the base member below the guide roller;

IX. a first drive meansfor operating the first roller means which:

A. is positioned exterior of the base member; B. engages the first roller means;

X. a second drive means for operating the second roller means which:

A. is positioned exterior to the base member; B. engages the second roller means; C. is driven by engagement with a motor;

XI. means linking the second drive means with the first drive means for transmitting driving force to the first drive means;

XII; a main wire guide means for receiving and guiding the metal wire section into an evaporation source which:

A. is mounted on the base members; and B. is positioned ahead of the guide roller means and second roller means. i 2. The apparatus of claim 1 which includes a secondary wire 7 guide means which:

' deposition of the metal on a substrate, which includes, in combination:

. I. a generally U-shaped base member which:

A. has a forward wall member;

B. has spaced apart upstanding side wall members; II. a hollow, generally cylindrical housing which:

A. has an outwardly directed flange integral with a rear portion of the housing which:

1. is secured to the sidewall members of said base member; 2. has an indexing motor mounted thereon;

B. has an inwardly directed flange integral with a forward portion of the housing; said flange having an opening therein at the bottom center position of the flange;

III. a generally cylindrical drum member which:

A. has a front journal rotatably mounted in said inwardly directed flange;

B. has a rear journal with a central bore portion therein adapted for engagement with a shaft on said indexing motor;

C. has at least one wire retaining means positioned on the periphery of the drum;

IV. a first yoke means which is pivotally mounted between the sidewall members of said base member;

V. a first feed roller rotatably mounted on a shaft, wherein said shaft:

A. extends between said sidewall members;

B. engages said first yoke means;

VI. a first drive sprocket which:

A. is mounted exterior to one of said sidewall members on the shaft containing the first feed roller;

B. is engaged by a bead chain drive,

VII. a second yoke means which:

A. is pivotally mounted between the sidewall members of the base member;

B. is positioned ahead of the first yoke means;

VIII. a guide roller rotatably mounted on a shaft, wherein the shaft:

A. extends between the sidewall members of the base member;

B. is positioned ahead of the first feed roller; C. engages the second yoke means,

IX. a second feed roller rotatably mounted on a shaft, the shaft extending between the sidewall members of the base member at a point below the guide roller;

X. a second drive sprocket which:

A. is mounted exterior to one of said sidewall members on the shaft containing the second feed roller;

B. is linked to the first drive sprocket by the head chain drive;

C. is driven by engagement with a motor;

Xi. a main wire guide means which:

A. is positioned ahead of the guide roller and second feed roller;

B. extends through andis secured to the forward wall member of the base member; and

C; has a bore portion which is in horizontal alinement with the opening in the inwardly directed flange of the cylindrical housing.

4. The apparatus of claim 3 which includes a secondary wire guide means which:

A. is attached to the base member;

B. is positioned behind the guide roller and the second feed roller;

C. has a bore portion which is in horizontal alinement with the opening in the inwardly directed flange of the cylindrical housing and with the bore portion in the main wire guide means.

5. The apparatus of claim 3 which includes means associated with the first yoke means for urging the first feed roller against a metal wire section positioned in one of the wire retaining means of the cylindrical drum member as said wire retaining means is rotated to the bottom center position of vthe drum.

6. The apparatus of claim 5 wherein the urging means associated with the first yoke means is defined by a machine screw which:

A. extends through and is spring-biased against a shoulder portion of the first yokemeans; and

B. threadedly engages a support bar extending between and secured to the sidewall members of the base member.

7. The apparatus of claim 3 which includes means associated with the second yoke means for urging the guide roller against a metal wire section during advance of said wire section through the main wire guide means.

8. The apparatus of claim 7 wherein the urging means associated with the second yoke means is defined by a machine screw which:

A. extends through and is spring-biased against a shoulder portion of the second yoke means; and

B. threadedly engages a support bar extending between and secured to the sidewall members of the base member.

9. The apparatus of claim 3 wherein the wire retaining means of the drum member is defined by a plurality of grooves which:

A. are positioned on the periphery of said drum member;

and

B. extend lengthwise of said drum member. 

